Forms a water-specific Channel (PubMed: 8621489, PubMed: 18768791). Plays an important role in fluid secretion in salivary glands (By similarity). Required for TRPV4 activation by hypotonicity. Together with TRPV4, controls regulatory volume decrease in salivary epithelial cells (PubMed: 16571723). Seems to play a redundant role in water transport in the eye, lung and in sweat glands (By similarity).